Biomedical subjects

T S Church

Publications and source records attributed to T S Church.

7 recordsLinked to original sources

PubMed2005

Obesity, macrophage migration inhibitory factor, and weight loss.

OBJECTIVE: Elevated macrophage migration inhibitory factor (MIF) has been implicated as a causal mechanism in a number of disease conditions including cardiovascular disease (CVD), diabetes, and cancer. Excess body fat is associated with an increased risk of numerous health conditions including CVD, diabetes, and cancer. To our knowledge, the association between MIF and obesity status and the effect of weight loss on serum MIF concentrations have not been reported. In this study, we examined the effects of participation in a behavior-based weight loss program on MIF concentrations in obese individuals. SUBJECTS: Study participants were 71 men and women enrolled in The Cooper Institute Weight Management Program. Participants were predominantly female (68%, n=48), middle-aged (46.5+/-9.8 y), and severely obese (BMI=43.0+/-8.6). METHOD: Plasma MIF concentrations and other standard risk factors were measured before and after participation in a diet and physical activity based weight management program. RESULTS: The mean follow-up was 8.5+/-3.0 months with an average weight loss of 14.4 kg (P<0.001). The majority of clinical risk factors significantly improved at follow-up. Median levels of plasma MIF concentration were significantly lower at follow-up (median [IQR]; 5.1[3.6-10.3]) compared to baseline (8.4 [4.3-48.8]; P=0.0005). The percentage of participants with plasma MIF concentration > or =19.5 mg/nl (highest tertile at baseline) decreased from 33.8 to 5.6% (P<0.001). Further, elevated baseline plasma MIF concentration was associated with markers of beta-cell dysfunction and reductions in MIF were associated with improvements in beta-cell function. CONCLUSIONS: Circulating MIF concentrations are elevated in obese but otherwise healthy individuals; however, this elevation in MIF is not uniform across individuals. In obese individuals with elevated circulating MIF concentrations, participation in physical activity and a dietary-focused weight management program resulted in substantial reduction in MIF.

Adult↗

PubMed2004

Relation between physical exertion and heart rate variability characteristics in professional cyclists during the Tour of Spain.

BACKGROUND: Continued exposure to prolonged periods of intense exercise may unfavourably alter neuroendocrine, neuromuscular, and cardiovascular function. OBJECTIVE: To examine the relation between quantifiable levels of exertion (TRIMPS) and resting heart rate (HR) and resting supine heart rate variability (HRV) in professional cyclists during a three week stage race. METHOD: Eight professional male cyclists (mean (SEM) age 27 (1) years, body mass 65.5 (2.3) kg, and maximum rate of oxygen consumption (VO(2)max) 75.6 (2.2) ml/kg/min) riding in the 2001 Vuelta a España were examined for resting HR and HRV on the mornings of day 0 (baseline), day 10 (first rest day), and day 17 (second rest day). The rest days followed stages 1-9 and 10-15 respectively. HR was recorded during each race stage, and total HR time was categorised into a modified, three phase TRIMPS schema. These phases were based on standardised physiological laboratory values obtained during previous VO(2)max testing, where HR time in each phase (phase I = light intensity and less than ventilatory threshold (VT; approximately 70% VO(2)max); phase II = moderate intensity between VT and respiratory compensation point (RCP; approximately 90% VO(2)max); phase III = high intensity (>RCP)) was multiplied by exertional factors of 1, 2, and 3 respectively. RESULTS: Multivariate analysis of variance showed that total TRIMPS for race stages 1-9 (2466 (90)) were greater than for stages 10-15 (2055 (65)) (p<0.0002). However, TRIMPS/day were less for stages 1-9 (274 (10)) than for stages 10-15 (343 (11)) (p<0.01). Despite a trend to decline, no difference in supine resting HR was found between day 0 (53.2 (1.8) beats/min), day 10 (49.0 (2.8) beats/min), and day 17 (48.0 (2.6) beats/min) (p = 0.21). Whereas no significant group mean changes in HR or HRV indices were noted during the course of the race, significant inverse Pearson product-moment correlations were observed between all HRV indices relative to total TRIMPS and TRIMPS/day accumulated in race stages 10-15. Total TRIMPS correlated with square root of mean squared differences of successive RR intervals (r = -0.93; p<0.001), standard deviation of the RR intervals (r = -0.94; p<0.001), log normalised total power (r = -0.97; p<0.001), log normalised low frequency power (r = -0.79; p<0.02), and log normalised high frequency power (r = -0.94; p<0.001). CONCLUSION: HRV may be strongly affected by chronic exposure to heavy exertion. Training volume and intensity are necessary to delineate the degree of these alterations.

Adult↗

PubMed2002

Associations between cardiorespiratory fitness and C-reactive protein in men.

OBJECTIVE: This study examined the association between cardiorespiratory fitness and C-reactive protein (CRP), with adjustment for weight and within weight categories. METHODS AND RESULTS: We calculated median and adjusted geometric mean CRP levels, percentages of individuals with an elevated CRP (> or =2.00 mg/L), and odds ratios of elevated CRP across 5 levels of cardiorespiratory fitness for 722 men. CRP values were adjusted for age, body mass index, vitamin use, statin medication use, aspirin use, the presence of inflammatory disease, cardiovascular disease, and diabetes, and smoking habit. We found an inverse association of CRP across fitness levels (P for trend<0.001), with the highest adjusted CRP value in the lowest fitness quintile (1.64 [1.27 to 2.11] mg/L) and the lowest adjusted CRP value in the highest fitness quintile (0.70 [0.60 to 0.80] mg/L). Similar results were found for the prevalence of elevated CRP across fitness quintiles. We used logistic regression to model the adjusted odds for elevated CRP and found that compared with the referent first quintile, the second (odds ratio [OR] 0.43, 95% CI 0.22 to 0.85), third (OR 0.33, 95% CI 0.17 to 0.65), fourth (OR 0.23, 95% CI 0.12 to 0.47), and fifth (OR 0.17, 95% CI 0.08 to 0.37) quintiles of fitness had significantly lower odds of elevated CRP. Similar results were found when examining the CRP-fitness relation within categories of body fatness (normal weight, overweight, and obese) and waist girth (<102 or > or =102 cm). CONCLUSIONS: Cardiorespiratory fitness levels were inversely associated with CRP values and the prevalence of elevated CRP values in this sample of men from the Aerobics Center Longitudinal Study.

Body Mass Index↗

PubMed2002

Relative associations of fitness and fatness to fibrinogen, white blood cell count, uric acid and metabolic syndrome.

OBJECTIVE: To examine the relation between fitness and fibrinogen, white blood cell count, uric acid and metabolic syndrome across levels of adiposity in apparently healthy, nonsmoking men. DESIGN: Cross-sectional study of 4057 men from the Aerobics Center Longitudinal Study examining the age-adjusted resting levels and risk of having a clinically significant elevation of fibrinogen, white blood cell count, uric acid and metabolic syndrome score across nine fitness-body fatness combinations. Fitness categories (low fitness, moderately fit or high fitness) were based on a maximal treadmill test. Body mass index (BMI) <25.0 was classified as normal weight, BMI > or = 25.0 but <30.0 as overweight and BMI > or = 30.0 as obese. RESULTS: Fitness (inversely) and BMI (directly) were independently related to the age-adjusted values of all four variables (P for trend P<0.0001 for each). For all four variables, the greatest age-adjusted risk of having a clinically relevant value was found in the low fitness-obese category and the lowest age-adjusted risk was found in the high fitness-normal weight group. CONCLUSION: Fibrinogen, white blood cells, uric acid and metabolic syndrome score are independently related to both fitness (inversely) and fatness (directly). Within levels of fatness, risk for significant elevations in fibrinogen, white blood cells, uric acid and metabolic syndrome score is lower for the higher fitness groups.

Adipose Tissue↗

PubMed2001

Usefulness of cardiorespiratory fitness as a predictor of all-cause and cardiovascular disease mortality in men with systemic hypertension.

There is an inverse gradient of mortality across levels of cardiorespiratory fitness in healthy adults; however, the association of fitness to mortality in persons with comorbidities such as hypertension is not fully understood. This study quantifies the relation of cardiorespiratory fitness to all-cause mortality and cardiovascular disease (CVD) mortality in hypertensive men. In this observational cohort study, we calculated death rates for low, moderate, and high fitness categories in normotensive (n = 15,726) and hypertensive (n = 3,184) men, and in men without a history of hypertension but with elevated blood pressure (BP) (systolic BP > or = 140 or diastolic BP > or = 90 mm Hg) at baseline (n = 3,257). The participants were 22,167 men (average age 42.6 +/- 9.2 years [mean +/- SD]) who underwent a medical examination that included a maximal exercise test during 1970 to 1993, with mortality follow-up to December 31, 1994. We identified 628 deaths (188 from CVD) during 224,173 man-years of observation. There was an inverse linear trend across fitness groups for all-cause and CVD mortality. The relative risk (95% confidence interval [CI]), using the low fitness group as reference, for all-cause mortality in hypertensive men was 0.45 (95% CI 0.31 to 0.65) and 0.42 (95% CI 0.27 to 0.66) for moderate and high fitness groups, respectively, and in men with elevated BP, 0.49 (95% CI 0.34 to 0.70) and 0.44 (95% CI 0.29 to 0.68) for moderate and high fitness groups, respectively. The pattern of results was similar for CVD mortality. There was an inverse linear relation between fitness and death rate for all-cause mortality in both the uncontrolled and controlled hypertensive groups. This study provides evidence that moderate to high levels of cardiorespiratory fitness provide protection against all-cause and CVD mortality in hypertensive men and men without a history of hypertension but with elevated BP at examination.

Adult↗

PubMed2001

Evaluating the reproducibility and validity of the Aerobic Adaptation Test.

PURPOSE: To examine the reproducibility and validity of a new submaximal, ramped cycle ergometer testing methodology known as the Aerobic Adaptation Test (AAT), which attempts to detect changes in submaximal work capacity and minimize participant discomfort. METHODS: 36 sedentary men (mean age = 48.1 +/- 10.2 yr [SD]) and 22 sedentary women (mean age = 51.9 +/- 10.2 yr [SD]) participated in the study. To test reproducibility, participants were tested twice with an average of 20 d between tests (+/-15 d). To test validity, participants were tested before and after a 6-month physical activity intervention, and outcomes were compared with standard measures of fitness (exercise time and oxygen consumption at 70% max heart rate). The main outcome variable of the AAT was work output (W) over a period of 3 min after reaching 70% maximal heart rate. RESULTS: The average work output at 70% HRmax was highly reproducible, with a test-retest reliability of rho = 0.85 (P < 0.001). Average work output at 70% HRmax significantly increased after 6 months of physical activity intervention (87.8 +/- 32.9 W vs 95.5 +/- 37.9 W, P = 0.002), and changes in average work output at 70% HRmax correlated with changes in exercise time to elicit 70% HRmax (r = 0.87, P < 0.001) as well as changes in VO2 at 70% HRmax (r = 0.75, P < 0.001). Thus, the AAT appears to be a valid measure of submaximal work capacity. CONCLUSIONS: The AAT is a reproducible and valid measure of submaximal work capacity that can serve as an effective means to evaluate physical activity interventions.

Adaptation, Physiological↗

PubMedDate not supplied

A rapid response microviscosimeter.

An in vitro instrument is described which is designed to measure effective viscosity of blood in arteriolar size tubes at physiologically nominal flow rates, mimicking flow in the microcirculation. The 41-micron microviscosimeter is accurate within 2% when tested against viscosity standards and is reproducible within 2% using blood samples. Because the full-scale instrument response time is 3 s, either fresh or anticoagulated blood samples may be used. Measured over the nominal range of blood flow rate (Q), effective blood viscosity was found to be an increasing, decreasing, or flat function of Q, depending upon the particular individual being tested. A reference group of 81 young, healthy subjects was used to define viscous resistance (VR), a new parameter that provides for quantitative viscosity comparisons between individuals or groups without hematocrit manipulation of blood samples. As examples of the microviscosimeter's use, a group of 118 subjects was used to test for VR variation between various group subsets. No difference in VR was found between men and women; exercisers had lower VR than nonexercisers; and overweight subjects had more viscous blood than non-overweight subjects. The instrument will be useful for in vitro investigations of effective viscosity and viscous resistance in the microcirculation.

Adult↗